<?php
// create a 100*30 image
$im = imagecreate(100, 20);

// white background and blue text
$bg = imagecolorallocate($im, 255, 255, 255);
$textcolor = imagecolorallocate($im, 0, 0, 255);

// write the string at the top left
imagestring($im, 5, 0, 0, "Hello world!", $textcolor);

// output the image
header("Content-type: image/png");
imagepng($im);
//usage : <img src="img_tag.php">
?> 